2
. Specifications
2.3. Characteristics of thermocouple temperature sensor input module
R200
Isolated Thermocouple Input Module TC4S User's Guide
27
September 2010
Honeywell
No
Thermocouple Sensor Type
ATTENTION
•
A thermocouple sensor measures temperature by using fine
voltage (electromotive force), which is generated when applying
temperature Rate Change to a junction between two different
metals.
•
The temperature-electromotive force relation specification of
normal thermocouple sensor provides the electromotive force,
which is measured when a sensor’s measuring point is at 0°C.
When temperature is measured using a thermocouple sensor,
cold junction compensation (reference junction compensation,
RJC) is used (built-in function of temperature measuring module).
Temperature conversion characteristics
The isolated thermocouple input module converts the thermocouple input with non-linear
characteristics into A/D and yields the temperature conversion that is linearly treated.
Temperature conversion to thermocouple input has non-linear characteristics.
ATTENTION
Non-linear characteristics: regarding the relation of temperature (°) and
electromotive force (
µ
V) of a thermocouple sensor, electromotive force is
different by sections even though temperature changes by a certain amount,
which is called ‘non-linear characteristics.’ As seen in the above graph, the
relation of temperature and electromotive force is a curve by temperature
sections. The module processes the non-linear characteristics table as linear.
Conversion speed
2MLF-TC4S has the conversion speed of 40ms per channel and processes channels
sequentially (operation/stop of each channel may be assigned independently).
Process time = 40ms
∗
no. of used channels
Example
: If using three channels: process time = 40ms
∗
3 = 120ms
